Obesity and the multitude of co-morbidities associated with obesity such as diabetes, dyslipidemia, coronary heart disease, and certain cancers are major concerns for public health. The affluence of the 90's along with the exponential increase in food production particularly in Western and Asian economies has resulted in feeding patterns that lead to obesity. Obesity is defined as being excessively overweight. Excessive weight is generally characterized by excessive body fat, because unused energy is stored in the adipose tissues as fat.
Obesity has associated with it, economic and social costs. Obese people, an increasing proportion of most western societies, are regarded as having out of control feeding habits often associated with low self-esteem. Moreover, obese persons are more likely to have medical problems associated with or exacerbated by the excess body weight. Examples of medical conditions caused, exacerbated, or triggered by excessive weight include bone fractures, pains in the knee joints, arthritis, increased risk of hypertension, atherosclerosis, stroke, and diabetes.
Melanin-concentrating hormone (MCH) has been identified as an orexigenic peptide that exerts an effect on food intake and body weight regulation. MCH is a cyclic 19 amino acid neuropeptide expressed in the zona incerta and lateral hypothalamus in response to both energy restriction and leptin deficiency. MCH is known to stimulate feeding when injected into the lateral ventricle of rats and the mRNA for MCH is upregulated in the hypothalamus of genetically obese mice (ob/ob) and in fasted control and ob/ob animals. In addition, animals treated with MCH show increases in glucose, insulin and leptin levels, mimicking human metabolic syndrome (Gomori, “Chronic Infusion of MCH Causes Obesity in Mice,” Am. J. Physiol. Endocrinol. Metab., 284:E583 (2002)). Mice lacking MCH are hypophagic and lean with increased metabolic rate, whereas animals over-expressing MCH gain excess weight on both standard and high fat diets. MCH is thought to have effects on other nervous system functions as well (Rocksz, “Biological Examination of Melanin Concentrating Hormone 1: Multi-tasking from the Hypothalamus,” Drug News Perspect., 19(5):273 (2006)). An orphan G-protein coupled receptor (GPCR) was recently identified as a receptor for MCH. Disruption of the binding between MCH and the MCH receptor, i.e. MCH antagonism, may thus be used to counteract the effects of MCH (McBriar, “Recent Advances in the Discovery of Melanin-Concentrating Hormone Receptor Antagonists,” Curr. Opin. Drug Disc. & Dev., 9(4):496 (2006)).
The current preferred treatment for obesity as well as Type II non-insulin dependent diabetes is diet and exercise with a view toward weight reduction and improved insulin sensitivity for diabetics. Patient compliance, however, is usually poor. The problem is compounded by the fact that there is currently only one medication approved for the treatment of obesity (orlistat (XENICAL™)).
The present invention is directed to overcoming these and other deficiencies in the art.